import java.util.Scanner;

class ZuHeShu{
  int zuheshu (int n,int m){
    if(m==1) return n;
    else if(m==0) return 1;
    else if(m==n) return 1;
    else if (n>m&&m>1&&n>1) return zuheshu(n-1,m-1)+zuheshu(n-1,m);
    else      return -1;
  }
}

public class diedai {
  public static void main(String[] args) {
    Scanner reader = new Scanner (System.in);
    System.out.println("输入m:");
    int m=reader.nextInt();

    System.out.println("输入n:");
    int n=reader.nextInt();

    ZuHeShu a =new ZuHeShu();

    if(a.zuheshu(n,m)==-1)
    System.out.println("输入数据有误");

    else
    System.out.println("C(n,m)="+a.zuheshu(n,m));
  }
}
